Heat supply control



Patented Aug. 25, 1953 UNITED STATES PATENT OFFICE 1 Claim.

This invention relating as indicated to a heating system is more particularly directed to a means for controlling the supply of fuel whether it be solid, gaseous or liquid. The invention may be used with hot water heating systems, as well as hot air or steam or vapor systems. In order to shorten the description, however, reference will be made to a stoker fired hot water system, but this is not intended as a limitation upon the invention as the invention may be applied to the control of any heating medium such as steam. For example, it is applicable to milk pasteurizing apparatus and other similar apparatus.

It is a particular object of the invention when applied to a stoker to interrupt the stoker operation at frequent intervals and for various periods, the number of interruptions and the length of such interruptions, measured in time, being controlled by the temperature of the heating medium which in the preferred example is the water in the boiler.

It is a further object of the invention to eliminate over heating by interrupting the heating operation of the heating apparatus at frequent intervals and in various cycles, the number of interruptions and the duration of such measured in time, being controlled by temperature. Continuous operation of a heating apparatus from the time the heatin starts until it is stopped by a predetermined setting of the temperature control (usually a room thermostat) builds up a reserve supply of heat in the heating apparatus causing overheating and waste of fuel. My invention is specifically designed to avoid overheating and its consequent waste.

Another object of the invention is to prevent overheating of a boiler and heating plant equipped with a summer-winter hookup. Such installations provide domestic hot water the year round. In this type of heating plant overheating is almost impossible to overcome with the conventional type of controls. Summer-winter heating systems are equipped with a thermostat, controlled circulating water pump and a flow valve. When the thermostat is satisfied it stops the circulator and the now valve closes leaving no way to dissipate the heat except by the domestic hot water load. A continuous run of the stoker from the time the boiler control starts it until it stops it, builds up such a fuel supply in the boiler fire box that it makes the boiler temperature rise very fast, which overheats the boiler to the point where the high limit control automatically starts the circulator again to relieve the excess boiler temperature.

This pumps hot water into the space to be heated when not needed. Sometimes a heating plant goes through several of these overheating cycles before the excess heat is dissipated from the fuel in the fire box after a shut down of the stoker.

My invention eliminates the above disadvantages since it starts cycling the interruptions of the fuel feeding into the boiler as the temperature begins to climb, giving the stoker longer interruptions per cycle as the temperature of the heating medium climbs so that when the thermostat is satisfied the deposits of fuel in the fire box are at a minimum.

It is another object of the invention to provide a control to be mounted in a relatively small cabinet or box containing a temperature actuated mechanism, a rotating means that turns a cam approximately one revolution per hour and a switch whose wires are employed to interrupt the operation of the heating apparatus. These wires are connected into the thermostat, boiler limit or operating control circuit. The only other installation is a connection between the temperature actuated mechanism and a heat responsive bulb which can be placed in the heating device, the boiler circulating loop or strapped to it.

It is a further object of the invention to provide a control with a minimum number of parts so that the cost thereof is exceedingly small.

A still further object of the invention is to provide a control wherein no manual adjustment is necessary, this control operating continuously and automatically.

A general object of the invention is to provide a cam member which is bodily movable toward and away from a switch so that contact of the switch with the cam makes and breaks the circuit which the switch controls, by braking the circuit for short intervals.

Another object of the invention is to save fuel by permitting the heating plant to have a combination of forced and natural heating, which permits the heating apparatus to absorb the heat better, which reduces the heat and stack losses, increases the eiiiciency and burning of the fuel, leaving a minimum size fuel bed and heat in the combustion chamber of the heating apparatus, thus preventing overheating of the heating apparatus and space to be heated.

A more detailed object of the invention is to provide a stationary switch mount having a movable switch arm which contacts the movable faces of a cam member.

Another specific object of the invention is to provide an alternative construction from that described in the preceding paragraph, wherein the switch mount is also stationary but the cam is bodily movable toward and away from a movable switch arm.

Another object of the invention is to automatically give oil and gas burners operating cycles after a shut down to prevent a condition called cold seventy.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claim.

The annexed drawing and the following description set forth in detail certain mechanism embodying the invention, suchidisclosed means constituting, however, but one of various mechanical forms in which the principle ofuthetinvention may be used.

"In said annexedcdrawing:

Fig. lie a diagrammatic View of :one form of the invention.

Fig. 2 is apartiabcentralsectionnf Fig. 1.

Fig. 3 is'a diagrammatic :view 'of amodification.

Referring-now :to the sdrawings, 'andwparticularly Fig. 1, it will besseen that I have provided abulb H which is adapted" to :be inserted in the boiler of avheatingi-system. This bulb communicates with a: bellows '68 by means .Of pipe iii, the bulb and iibellows preferably containing a 'hGatBXDHlHSibIE'EfiUid. The ;belloWs is mounted in any desired manner.

Wire i8 is :connected to screw is, this Wire leadingfrorn the operating control (not shown) which-may obviously be' placed in any desired position. The' otherwire' I! leads from screw i5 to" the: heating v d'evicaso that when the cam 'contacting-"-member 5'3 iislpushed to the left as viewed :in Fig. l, the button PSI :is depressed and the" circuit is brokentbetween lines l.6.;-and l l. Arm 2 extends" upwardly: from'ztheswitch, 'this a-rm preferably being formedsof spring metal and being adapted to engage scam. :faces155 n the cam plate.

The switch fiil isstationarily:mountedrand the cam faces 55 are pivotally mounted.

The campmtaessactuatedzb some'suchime'ans asa clockwork-mechanism (not shown) :is mounted upon shafttil (see Fig.2) the shaftbeing slidable axially-with: respecttotthe:cam. plate, the "earn- 1 plate being maintained. in* a plane'zby. .means not shown. A series -of links .ESare pivotedat: 55 to the shaft 3%, these links beingpivotedat. bl. to each of 'cam m'embers -ormovable cam: faces. 56. A sleeve-6i isseated in the outeriendxofshaft 69, this sleeve being-"provided with a. clevis: 6.2;.the clevis having a pin' 63 extending .therethrough. "The piniifl slidesin sl'ot 54 in link: 65:, andthelink $35 is pivoted at 66 to a' supportin 1=bracket. .A 'b'ellows iiilis connected by means of the pin. G'i to the link- 65. "'ihe biellows' E38 communicates with the bulb l by'means of the conduit 10.

In operation, the: temperature. in; .theuheating apparatus upon rising, causesfluid in-bulb :"l i to e2-1pand-thus expanding-bellows 68. This expansi-on causes shaft fi ilto slide-downwardlyas iviewed in" Fig; 2 and this, inturn causes' thedinks. 58:.to "force cam-faces 55- outwardly. The: button If. at

' this stage has not be'en depressed and 'the' circuit continues througli lines it 6. and il'lto operatewthe rstokeror heating apparatus. -rIn the-meantime, the campl-ate'ta-zis :revolving and-when the cam vface 55 contacts switch arm.-.-52..the -button BL is 4 depressed, thus breaking the circuit to the Stoker or heating apparatus and interrupting the operation thereof. This interruption will continue until one of the cam faces 55 has passed beyond the upper end of switch arm 52, whereupon switch arm 52 Will assume the position shown in Fig. 1. This causes the button 5| to move outwardly again making the circuit to the stoker of heatin apparatus. It will be noted that the length of theinterruptionzas Well-. as'zthe"-frequency of interruption, is automatically controlled by the temperature of the boiler water. This is due to the provision of means controlled by such temperatureto vary the distance between the switch arm 52 and cam faces 55. Thus it will be seen that --in this embodiment, the cam faces are moved, whereasin the succeeding embodiment, the whole cam is bodily moved.

.Referring to the modification shown in Fig. 3, in this embodiment the cam and the cam actuatingmeans reciprocate.soas-tomove the cam faces 82 toward and away from the button 18.0n switch arm .11.

The housing .H contains .a clockwork-mechanism or some similardeviceivhich will continuously rotate the cam C-3 in a clockwise direction about its-axis. ,The-housingand-cam moveas a unit along vthe-trackways l9 andBfl. The belloW B lisconnected tothepin-83 soas .to impart movement tothe housing .Thebulb lldissimilarto the bulb l l and isconnected to the .bellows 8.4 by the pipeor conduit .35.

In operation, fiuidin thebulb; 8B expands p heating and in turn this causes thebellowsfid to expand which'moves housing .H andcam-Ce3 t0 the left as viewed inFig. 3. As soon as a cam face 82 contacts the cam.contacting member, 7811 switch arm 'i'i depresses button .76. This movement opens the circuit thusshutting off current supply to the stoker orother apparatus which vi being controlled.

Conversely, ,upon. cooling of the bulb, 86 the bellows as contracts, sliding. the housingI-I to the right-and moving the cam C-3,.and.particularly its faces 82, out of contact withthe ,cam contacting member 18 on switch armll. ,This closes t .circuit. .The same effect is, obtainedwhenthe camin rotating passes along the-cam contactin member 18 until such member reaches thesurface 8| whereupon the.spring. arm llmoves to the right again closing the circuit to the stoker for example.

=While the inventionhas been described in con- .nectionwitha stoker it .canbe usedwith oil and gas burners and'also in other fields. For example, in pasteurizingmilk, live steam is fed into the water: in the pasteurizer .jacket and unless this steamsupply ,is cuton and off intermitten ly .as the temperature rises, the milk willscorch. In

thisprocess his .most important that the temp.erature of .themilkrises gradually.

The invention as. used in pasteurizin milk .would'have theactuating bulb l tor -86, placed in the, jacket around .the pasteurizerand the temperature control in the milk. ,In this casethelnyention opens and closes the steam. valve inter- .mittently, shortening, the heatingperiods ,as the temperature rises.

. From .theforegoing description, .it.will beseen that. I ,have provided a. heating .controlwherein interruption of .theheating apparatus takes place as the temperatureofthe heatingmedium rises .or falls. .can be broken in periods of any desired. length .It will also. be notedthat the circuit and l at any desired frequency, depending. upon the configuration of the cam faces. It will also be noted that my control is entirely automatic and it is not necessary to make manual adjustments. As far as I am aware, there are no prior constructions involving interruptions of the stoker or heating device performance for longer periods of time as the temperature of the heating apparatus increases and vice versa.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein discloses, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

This application is a continuation-in-part of my co-pending application, Heat Supply Control, Serial No. 634,300, which issued as Patent No. 2,488,572 on [November 22, 1949.

I therefore particularly point out and distinctly claim as my invention:

A fuel supply control for a heating system, said control comprising a, temperature responsive means operated by the heating medium of said system, a snap action switch, a rotating cam member having a series of cam faces, a spring arm on said switch adapted to contact said cam faces, and means actuated by the temperature responsive means to vary the distance between said spring arm and said cam faces by moving the cam faces of said rotating cam member toward and away from said spring arm, the contacts of said switch being closed and thus operating said fuel supply when said spring arm is out of contact with any of said cam faces, said switch contacts being immediately opened when said spring arm is in contact with a cam face and remaining open as long as said spring arm contacts a cam face whereby increase of temperature of said heating medium causes increase in duration of the off cycle and decrease in temperature of the heating medium causes increase in duration of the on cycle.

FRANK M. VARNEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,767,636 Willijelm June 24, 1930 2,185,759 Young Jan. 2, 1940 2,291,840 Spangenberg Aug. 4, 1942 2,373,186 Isserstedt Apr. 10, 1945 2,488,572 Varney Nov. 22, 1949 

